This invention relates to laboratory equipment and more particularly to apparatus for washing and cleaning contaminated test tubes, flasks and the like used in laboratory work.
In radioimmunoassay testing, for example, one problem encountered is safe disposal of radioactive (contaminant) material after separation of free and bound antibodies or antigens. Radioimmunoassays are in vitro laboratory test procedures increasingly used to determine small amounts of molecules, e.g. antigens, antibodies, hormones, or drugs, because radioimmunoassay testing combines the sensitivity of radioactivity counting with the specificity of antigen-antibody binding.
During such tests, there should be a consistent and complete washing of solid phase radioimmunoassay tubes after incubation and before counting. A radioimmunoassay for hepatitis associated antigen (HAA) serves as an example. Reagent tubes for this test would contain an inside, bottom sandwiched layer consisting of an antibody attached to the inside of the tube and radioactive (labeled) antigen attached to the antibody. Patient serum is precisely diluted in a buffer and a measured amount of the dilution is introduced into the tube whereupon the tube is incubated at a preset temperature for a specified period of time.
During the incubation, hepatitis antigen in the patient's serum will compete with the labeled antigen for the antibody binding sites and will displace some of the labeled antigens; the more antigen that is present in the serum, the more labeled antigen will be displaced. At the end of the incubation period, liquid in the tube is removed and the inside of the tube is washed to insure complete removal of displaced, "free" labeled antigen. The radioactivity of the tube, i.e., the amount of labeled antigen left in the tube is counted by introducing the entire tube into a radioactivity counter, typically a gamma radiation counter. The more radioactivity there is measured, the less antigen there was present in the patient's serum and vice versa.
To obtain consistent results, it is important that the washing of the tube before counting of the radioactivity be gentle but consistent, i.e., the same volume of wash fluid should be used for each tube; gentle so as not to loose bound, labeled antigen. Consistency is necessary for the following reason:
Typically, the radioimmunoassay is calibrated by using sera with known amounts of antigen instead of patient sample. Several sera containing various amounts of antigen are run in a batch with many patient sera and a calibration curve is established based upon the radioactivity in the tubes where calibrator sera were used. The amount of antigen in the patient sera is determined from the calibration curve. Since the amount of bound antigen in the tubes may to some extent depend upon the amount of washing, or some free, labeled antigen may stick to the inside of the tube if not completely washed before counting, it is necessary to be sure that the washing is consistent.
Typically, containers are presently cleaned by first inverting them so that material in the container, including contaminants, flows out the container mouth and into a waste receptacle. Alternately, a suction probe is introduced into the container and material is drawn off through the probe to the receptacle by aspiration. Next, the inside of the container is cleaned with a wash solution which is discharged into the container from a dispensing mechanism such as a syringe dispenser. The dispenser may be adjusted to discharge a predetermined volume of solution into the container and for this purpose has valves which are operated with one hand while the other hand reintroduces the probe into the container after a discharge of solution into it. Since many washes may be necessary to adequately clean the container, the above process may need to be repeated numerous times. The procedure, as outlined, is both tedious to perform and requires the use of both hands to be done properly.
A test tube washer operable with one hand is disclosed in U.S. Pat. No. 3,849,830 and is a handheld unit having a probe for insertion into a test tube and two ports which the user covers with his thumb to draw wash solution, by aspiration, through the probe for circulation around the inside of the test tube with one of the ports then being uncovered to stop the flow of solution to the probe and draw off the material in the test tube. While such a washer may make a cleaning operation less tedious, it has the disadvantages of potentially bringing the material being aspirated into contact with the user, of not being usable with all sizes and types of laboratory containers, and of not accurately metering the amount of wash solution introduced into a test tube.